Sign an A4 page (adjust delta to height for other formats) with a scanned signature by overlaying them
pdfjam {{path/to/file.pdf}} {{path/to/signature}} --fitpaper true --outfile {{path/to/signed.pdf}} --nup "{{1x2}}" --delta "{{0 -842pt}}"
pdfjam {{path/to/file.pdf}} {{path/to/signature}} --fitpaper true --outfile {{path/to/signed.pdf}} --nup "{{1x2}}" --delta "{{0 -842pt}}"